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I. Field defined: study of mechanisms that allow organisms to respond to their environment.

Physiological Ecology. I. Field defined: study of mechanisms that allow organisms to respond to their environment. II. Light & Plant Life A. all production except for chemosynthetic bacteria is due to autotrophic “self-feeders”

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I. Field defined: study of mechanisms that allow organisms to respond to their environment.

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  1. Physiological Ecology I. Field defined: study of mechanisms that allow organisms to respond to their environment. II. Light & Plant Life A. all production except for chemosynthetic bacteria is due to autotrophic “self-feeders” B.quality (spectral composition) & quantity(amount of energy) of light change with depth

  2. What are the possible adaptations for optimal light gathering? 1. photoacclimation through pigment production 2. changes in photosynthetic rates: sun vs. shade responses 3. reorientation of chloroplasts 4. phototactic & phototrophic responses 5. day length timing of reproduction 6. moving chloroplasts into epidermis: seagrasses 7. thickness of mangrove upper leaves 8. xeromorphy: adaptation to H2O deficiencies

  3. Pigments & Light-Harvesting Antennas 1. Pigment Structure (Recognize structures!) a. chlorophyll (a, b, c) b. carotenoid ( carotene, siphonoxanthin, fucoxanthin) c. phycobilins (phycoerythrin, phycocyanin) 2. Structure of photosynthetic membrane 3. Process of photosynthesis 4. Action Spectra Vs. Absorption Spectra 5. Phylogenetic chromatic adaption? 6. Intensity adaptation by increasing total pigments?

  4. Chlorophyll a & b

  5. Carotenoids b-Carotene siphonoxanthin fucoxanthin

  6. Phycobilins

  7. Actionvs.AbsorptionSpectra

  8. A photosystem consists of an antenna and a reaction center.

  9. Chloroplast Lumen Thylakoid Stroma

  10. How do marine plants protect from UV? 1. UV- absorbing compounds: Gracilaria chilensis makes more if exposed to UV 2. Ulva decreases growth, increase UV = decrease Ulva 3. UV damages photosynthetic apparatus, blue-light exposure helps plant recover. 4. Problems with decreased O3?

  11. Sun (HLP) & Shade (LLP)plantsA. General Model B. Changing # of traps, fixed antenna sizeC. Fixed # of traps, changing antenna size

  12. Light as a Signal 1. growth: photomorphogenic & phototropic (phytochrome: red/far red switch) 2. development: photoperiodic a. germination b. growing toward light in a shaded situation 3. types of responses to day length a. short-day plants: respond to photoperiods less than a critical day length ex. Monostroma grevillei: daylength determines life-history stage b. long-day: respond to photoperiod more than a critical day length c. day-neutral: photoperiod not critical

  13. Carbon Fixation: CO2 as C source for photosynthesis 1. diffusion in water 104 X slower than air 2. boundary layer restricts further 3. some seaweeds use HCO3- via carbonic anhydrase 4. primary photosynthetic pathway of CO2 fixation is C3 pathway (Calvin cycle) a. enzyme involved = RuBisCO, most abundant protein on the earth!!!!!!! = ribose-1,5-bisphosphate carboxylase oxygenase b. C3 because 1-5C molecule + CO2 = 2-3C backbones=> eventually becomes 6C (glucose).

  14. Carbon Fixation

  15. Photorespiration: net loss of fixed C => bad deal for the plant. 1. Why? RuBisCO can fix O2 as well as CO2, but don’t get sugar as a result 2. Some monocots solve this problem via the C4 pathway and an enzyme called PEPck, or phosphoenol pyruvate carboxylase. a. grasses isolate theRuBisCO into internal cells b. PEPck resides in outermost photosynthetic cells, grabs CO2 into a C4 compound c. the C4 compound is shuttled into an internal cell within the leaf where CO2 is pulled off and fed into the C3 pathway. d. works best in warm, high light environments, where there is plenty of sunlight energy: C4 pathway is energetically expensive

  16. Photorespiration

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